Ok so my car threw a service engine soon light. I put my scan tool on it and it said coolant temp was to low. I have a zzp thermostat coming in the mail (180* drilled), so when i get that im going to put that in. And i am going to pick up a temp sensor at autozone but was wondering if i have to drain coolant to change that sensor? If so how do i do that and is it easy?